Low magnification micrograph of a thecoma. Thecomas are benign ovarian tumours that belong to the sex cord-stromal tumour group and are thought to arise from the ovarian medulla.

Histologic features (seen in image):

• Nuclei with oval to spindle morphology.
• Abundant cytoplasm that is pale, vacuolated.
• Compression of the ovarian cortex (right aspect of image).

These tumours can be differentiated from fibroma with alpha-inhibin staining. Also, fibromas lack the characteristic vacuolization of the cytoplasm.

• Image:thecoma_high_mag.jpg - high magnification view of the same tumour.